The present invention relates to an apparatus for processing a veneer such as squeezing water out of a veneer for dehydrating it and forming short splits in a veneer for tenderizing it.
A crude veneer generally has a water content ranging from 30 percent to 200 percent and needs some treatment to serve as a ply, for example. One implementation available for dehydration of crude veneers is mechanical drying which squeezes out water by compression, as proposed in Japanese Unexamined Patent Publication (Kokai) No. 48-49905 and others. The prior art mechanical drying system uses compressing members such as rolls which act on the whole surfaces of a crude veneer to squeeze water thereoutof. The problem with this system is that although the processing may consume far less energy and far shorter period of time than an evaporation type drying system which uses a dryer, a veneer is inevitably subjected to compressive deformation over the entire surfaces thereof and, thereby, plastically deformed in a thicknesswise direction thereof and/or broken down. Specifically, to remove a greater amount of water, a greater amount of compressive deformation of a veneer is required. Such compressive deformation would impose excessive loads on the tissues of veneers considerably affecting the quality of a product made of the veneers, e.g. plywood. For this reason, it has been customary to control the amount of deformation to below a relatively small one sacrificing the amount of water which is removable from veneers.
Another prior art dehydration system for veneers is implemented with rolls each having tooth-like projections on its peripheral surface, as disclosed in Japanese Patent Publication Nos. 52-9712 and 56-32547. However, even such a system cannot constitute a solution to the above-discussed problem. Specifically, the tooth-like projections, or teeth, on each roll are directed to eliminating irregular splits otherwise formed in veneers during compression, the compression still being performed bythe roll peripheries other than the teeth. The distance between the peripheries of the rolls except for the teeth, or bottom lands, is not greater than about 30-60 percent of the thickness of a veneer, so that the rolls cause a veneer to undergo plastic deformation over the entire surfaces against which the rolls are abutted.
Meanwhile, there has been proposed a tenderizing apparatus in which a veneer is passed through, for example, a pair of rolls at least one of which is provided with narrow compressing elements, as shown and described in Japanese Patent Publication No. 49-39808. The rolls compress a veneer to deform and thereby form splits in it. This type of tenderizing apparatus cannot form splits in a veneer unless it applies a sufficient degree of pressure thereto so that, where the surfaces which act on a veneer are substantially flat such as those of the above-mentioned compressing elements, the required compressing force is considerable. The apparatus therefore cannot avoid a complicated and expensive construction. Another disadvantage is that since the gap between the compressing elements and the other roll or other compressing elements cannot be reduced beyond a value approximate to zero at maximum, the expected tenderizing effect is unattainable depending upon the physical properties of a veneer.
An apparatus for processing a veneer of the present invention comprises a pair of rotary bodies each being provided on an outer periphery thereof a number of teeth edge lines of which extend each in a direction that intersects an intended direction of rotation of the rotary body. The rotary bodies are located such that the teeth thereon are aligned with each other in a predetermined position where the veneer is inserted. The edge of each of the teeth is indented along the edge line to have alternating projections and recesses. Tips of the projections of the teeth on one rotary body and those of the projections of the rotary body assume a predetermined relative position in the predetermined position for veneer insertion. The apparatus also comprises a resilient material which fills the recesses of the teeth which neighbor each other on each of the rotary bodies.
The words "edge line" of a tooth repeatedly mentioned herein generally refers to a one which is parallel to an axis of rotation, a one which intersects an axis of rotation at a predetermined angle, a one which spirally intersects an axis of rotation at a predetermined angle, a one which extends in a zig-zag configuration along an axis of rotation, etc. The word "tooth" on the other hand covers a one whose section in a plane perpendicular to the edge line, or profile, is triangular and a one the edge of which is not sharpened and, instead, provided with a tooth crest.
In accordance with the present invention, a dehydrating effect is predominant when a veneer is inserted into the apparatus in such an orientation that fibers thereof extend substantially parallel to the direction of insertion, and a tenderizing effect when it is inserted in such an orientation that the fibers extend substantially perpendicular to the direction of insertion. Although such has been proved by experiments, the apparatus in the instant specification is positively referred to as a veneer processing apparatus because which one of the two different effects is to be chosen depends upon the person.
Further, that the projections and recesses of one rotary body interlock with those of the other rotary body implies a condition wherein the projections protrude into the recesses. Meanwhile, that the projections on the facing rotary bodies are spaced from each other by an amount which is smaller than the thickness of a veneer implies a condition wherein the projections on the rotary bodies, more precisely the tip cylinders each passing through the tips of the projections of the rotary body, are aligned with each other or spaced apart from each other by an amount which is smaller than the thickness of a veneer. Therefore, the situation concerned with the spacing covers both a case wherein the projections of the two rotary bodies are aligned with each other, and a case wherein they are deviated from each other by half a pitch such that the projections of one rotary body are aligned with the recesses of the other rotary body.